This invention relates to a safety needle accessory and in particular to safety needle accessory incorporating a protective pack. Safe hypodermic needles reduce the risk of needle stick injuries, and are increasingly specified in many healthcare areas as a means of reducing cross-infection with serious diseases. Generally, these devices employ a sliding sleeve which is biased towards the sharp tip of the needle, so that after use, the end of the sleeve prevents easy access to the needle tip. The sleeve may be operated manually, so-called “active” safety needles, or automatically, known as “passive” safety needles. Passive needles are preferred because the needle is covered during the whole of the injection procedure, and as the needle is withdrawn, the sleeve slides towards and then covers the needle tip. The whole procedure is automatic and independent of the user. In most cases, the sleeve locks in the safe position to prevent inadvertent contact with the needle, and to prevent re-use.
Most safety needles are sold separately as accessories, whereby the user puts the device onto a pre-filled syringe. Good practice requires that the syringe is filled with a different needle to the needle that is to be inserted in the patient. The reasons are that the rubber seal on the vial from which the medicament is withdrawn may have surface contamination, or a piece of the rubber seal may partially block the needle (“coring”), and the small needles used for many injections have a low flow rate, which, during filling, can cause foaming of the medicament. Thus, a large needle might be used to fill the syringe, which is then removed and replaced by the small injection needle. However, even in the most assiduous of healthcare practices, frequently the same needle is used to fill the syringe and to inject the patient. This is probably because despite the theoretical risks, in practice, many billions of injections have been given without problems. It is often preferred that the needle tip is exposed for 4-5 mm prior to use, to facilitate aspiration of air trapped in the syringe, and to enable accurate placement on the injection site. Apart from the risk of an unpleasant scratch from the exposed needle tip, there is practically no risk of cross-infection, since the needle has not been used to inject a patient.
A problem arises with safety needles however, particularly with the preferred passive type. Usually with the passive types, the initial movement of the sleeve towards the syringe when injecting the patient enables the safety mechanism. Clearly, if such a needle were used to fill a syringe from a vial, the safety mechanism would operate and prevent the needle being used to inject a patient. The only solution would be to replace the used needle with a new one—which could be considered too expensive and time consuming.